Werther was an important and influential novel of the Sturm und Drang period. Goethe was 26 when he wrote it. It was his first novel and brought him instant fame. It is something of a young person's novel, overbrimming with emotional drama. In later life, Goethe distanced himself from it somewhat.
I found the early part too overheated for my taste (a bit too much of a Sturm in a teacup) but Werther's obsessive passion becomes more authentic and compelling later in the story. And, some way through the book, there are very fine descriptive passages. The ending is extraordinary - dark, dramatic, disturbing. It is difficult now to understand the impact the novel had at the time, as it was so perfectly suited to the zeitgeist, so different from our own.
I read the Modern Library Classics edition, translated and introduced by Burton Pike. I have not read other editions, so cannot compare them, but I can tell you that this one is excellent. Werther presents a particular challenge to the English translator, because it includes a sizeable extract from The Songs of Ossian, by James Macpherson, translated into German. So does the translator attempt a translation of Goethe's German version, which is rather more passionate and free-flowing than the original, or is it better to simply revert to the original English version? Pike chooses the latter course, wisely in my opinion, and adds an explanatory footnote. He also discusses the issue in the Introduction.
If you want to get to know Goethe's work (and if you enjoy good literature, you should) then this first novel is a logical place to start, but be assured that his more mature work is far better.